Channel structure for communication systems

ABSTRACT

A channel structure for use in communication systems. Two sets of physical channels, one for the forward link and another for the reverse link, are utilized to facilitate communication of a variety of logical channels. The physical channels comprise data and control channels. In the exemplary embodiment, the data channels comprise fundamental channels which are used to transmit voice traffic, data traffic, high speed data, and other overhead information and supplemental channels which are used to transmit high speed data. The fundamental channels can be released when the remote stations are idle to more fully utilized the available capacity. The control channels are used to transmit paging and control messages and scheduling information.

CROSS REFERENCE

This application is a divisional application of application Ser. No.08/931,535, filed Sep. 16, 1997, entitled “Channel Structure ForCommunication Systems” which is currently pending.

BACKGROUND OF THE INVENTION

I. Field of the Invention

The present invention relates to communications. More particularly, thepresent invention relates to a channel structure for communicationsystems.

II. Description of the Related Art

The use of code division multiple access (CDMA) modulation techniques isone of several techniques for facilitating communications in which alarge number of system users are present. Although other techniques suchas time division multiple access (TDMA) and frequency division multipleaccess (FDMA) are known, CDMA has significant advantages over theseother techniques. The use of CDMA techniques in a multiple accesscommunication system is disclosed in U.S. Pat. No. 4,901,307, entitled“SPREAD SPECTRUM MULTIPLE ACCESS COMMUNICATION SYSTEM USING SATELLITE ORTERRESTRIAL REPEATERS,” and assigned to the assignee of the presentinvention and incorporated by reference herein. The use of CDMAtechniques in a multiple access communication system is furtherdisclosed in U.S. Pat. No. 5,103,459, entitled “SYSTEM AND METHOD FORGENERATING SIGNAL WAVEFORMS IN A CDMA CELLULAR TELEPHONE SYSTEM”,assigned to the assignee of the present invention and incorporated byreference herein. The CDMA system can be designed to conform to the“TIA/EIA/IS-95 Mobile Station-Base Station Compatibility Standard forDual-Mode Wideband Spread Spectrum Cellular System”, hereinafterreferred to as the IS-95 standard. Another code division multiple accesscommunication system includes the GLOBALSTAR communication system forworld wide communication utilizing low earth orbiting satellites.

CDMA communication systems are capable of transmitting traffic data andvoice data over the forward and reverse links. A method for transmittingtraffic data in code channel frames of fixed size is described in detailin U.S. Pat. No. 5,504,773, entitled “METHOD AND APPARATUS FOR THEFORMATTING OF DATA FOR TRANSMISSION”, assigned to the assignee of thepresent invention and incorporated by reference herein. In accordancewith the IS-95 standard, the traffic data and voice data are partitionedinto traffic channel frames which are 20 msec in duration. The data rateof each traffic channel frame is variable and can be as high as 14.4Kbps.

In the CDMA system, communications between users are conducted throughone or more base stations. A first user on one remote stationcommunicates to a second user on a second remote station by transmittingdata on the reverse link to a base station. The base station receivesthe data and can route the data to another base station. The data istransmitted on the forward link of the same base station, or a secondbase station, to the second remote station. The forward link refers totransmission from the base station to a remote station and the reverselink refers to transmission from the remote station to a base station.In IS-95 systems, the forward link and the reverse link are allocatedseparate frequencies.

The remote station communicates with at least one base station during acommunication. CDMA remote stations are capable of communicating withmultiple base stations simultaneously during soft handoff. Soft handoffis the process of establishing a link with a new base station beforebreaking the link with the previous base station. Soft handoff minimizesthe probability of dropped calls. The method and system for providing acommunication with a remote station through more than one base stationduring the soft handoff process are disclosed in U.S. Pat. No.5,267,261, entitled “MOBILE ASSISTED SOFT HANDOFF IN A CDMA CELLULARTELEPHONE SYSTEM,” assigned to the assignee of the present invention andincorporated by reference herein. Softer handoff is the process wherebythe communication occurs over multiple sectors which are serviced by thesame base station. The process of softer handoff is described in detailin copending U.S. patent application Ser. No. 08/763,498, entitled“METHOD AND APPARATUS FOR PERFORMING HANDOFF BETWEEN SECTORS OF A COMMONBASE STATION”, filed Dec. 11, 1996, assigned to the assignee of thepresent invention and incorporated by reference herein

Given the growing demand for wireless data applications, the need forvery efficient wireless data communication systems has becomeincreasingly significant. An exemplary communication system which isoptimized for data transmission is described in detail in copending U.S.patent application Ser. No. 08/654,443, entitled “HIGH DATA RATE CDMAWIRELESS COMMUNICATION SYSTEM”, filed May 28, 1996, assigned to theassignee of the present invention, and incorporated by reference herein.The system disclosed in U.S. patent application Ser. No. 08/654,443 is avariable rate communication system capable of transmitting at one of aplurality of data rates.

A significant difference between voice services and data services isthat the former requires a fixed and common grade of service (GOS) forall users. Typically, for digital systems providing voice services, thistranslates into a fixed and equal data rate for all users and a maximumtolerable value for the error rates of the speech frames, independent ofthe link resource. For the same data rate, a higher allocation ofresource is required for users having weaker links. This results in aninefficient use of the available resource. In contrast, for dataservices, the GOS can be different from user to user and can be aparameter optimized to increase the overall efficiency of the datacommunication system. The GOS of a data communication system istypically defined as the total delay incurred in the transfer of a datamessage. Another significant difference between voice services and dataservices is the fact that the former imposes stringent and fixed delayrequirements. Typically, the overall one-way delay of speech frames mustbe less than 100 msec. In contrast, the data delay can become a variableparameter used to optimize the efficiency of the data communicationsystem.

The parameters which measure the quality and effectiveness of a datacommunication system are the total delay required to transfer a datapacket and the average throughput rate of the system. Total delay doesnot have the same impact in data communication as it does for voicecommunication, but it is an important metric for measuring the qualityof the data communication system. The average throughput rate is ameasure of the efficiency of the data transmission capability of thecommunication system.

A communication system designed to optimize transmission of dataservices and voice services needs to address the particular requirementsof both services. The present invention provides a channel structurewhich facilitate transmissions of data and voice services.

SUMMARY OF THE INVENTION

The present invention is a novel and improved channel structure for usein communication systems. The present invention provides for two sets ofphysical channels, one for the forward link and another for the reverselink, to facilitate communication of a variety of logical channels. Thephysical channels comprise data and control channels. In the exemplaryembodiment, the data channels comprise fundamental channels which areused to transmit voice traffic, data traffic, high speed data, and otheroverhead information and supplemental channels which are used totransmit high speed data. In the exemplary embodiment, the forward andreverse traffic channels can be released when the remote stations areidle to more fully utilized the available capacity. The control channelsare used to transmit control messages and scheduling information.

It is an object of the present invention to provide a channel structurewhich supports voice services and data services. In the exemplaryembodiment, the traffic channels comprise fundamental and supplementalchannels. The fundamental channels can be used to transmit voicetraffic, data traffic, high speed data, and signaling messages. Thesupplemental channels can be used to transmit high speed data. In theexemplary embodiment, the fundamental and supplemental channels can betransmitted concurrently. In the exemplary embodiment, to improvereliability (especially for signaling messages) the fundamental channelsare supported by soft handoff.

It is another object of the present invention to provide a channelstructure which maximizes the throughput rate of a communication system.In the exemplary embodiment, the supplemental channels transmit at oneof a plurality of data rates. The data rate is selected based on a setof parameters which can comprise the amount of information to betransmitted, the transmit power available for the remote station, andthe required energy-per-bit. The data rate is assigned by a schedulersuch that the system throughput rate is maximized.

It is yet another object of the present invention to provide a channelstructure which optimizes transmissions from multi-cell andmulti-carrier. In the exemplary embodiment, the power levels of all basestations in the active set of the remote station are measuredperiodically during a communication. The multi-cell Δ power levels aretransmitted to the base stations which use the information to transmithigh speed data from the “best” set of base stations, thereby increasingcapacity. In addition, the power levels of all carriers are alsomeasured periodically and the multi-carrier Δ power levels aretransmitted to the base stations. The base stations can use theinformation to increase the power level of weak carriers or to reassignthe remote station to a new carrier assignment.

It is yet another object of the present invention to provide a channelstructure which minimizes power consumption and increase systemcapacity. In the exemplary embodiment, the remote station operates inone of three operating modes which comprise the traffic channel mode,the suspended mode, and the dormant mode. If the period of inactivitysince the termination of the last transmission exceeds a firstpredetermined threshold, the remote station is placed in the suspendedmode. In the exemplary embodiment, in the suspended mode, the trafficchannel is released but the state information is retained by both theremote station and the base station and the remote station monitors thepaging channel in the non-slotted mode. Thus, the remote station can bebrought back to the traffic channel mode in a short time period. If theperiod of inactivity exceeds a second predetermined threshold, theremote station is placed in the dormant mode. In the exemplaryembodiment, in the dormant mode, the state information is not retainedby neither the remote station nor the base station but the remotestation continues to monitor the paging channel in the slotted mode forpaging messages.

It is yet another object of the present invention to provide a channelstructure which minimizes processing delay for high speed datatransmissions. In the exemplary embodiment, the control data aretransmitted over control frames which are a fraction of the trafficchannel frame. In the exemplary embodiment, the data rate request by theremote station and other information are transmitted by the remotestation using a control channel frame format which minimizes theprocessing delay between the time a data rate request is made to thetime of actual transmission at the assigned data rate. In addition, thepresent invention provides for erasure-indicator-bits for both theforward and reverse links which can be used in place of NACK RLP framesdefined by the IS-707 standard.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, objects, and advantages of the present invention willbecome more apparent from the detailed description set forth below whentaken in conjunction with the drawings in which like referencecharacters identify correspondingly throughout and wherein:

FIG. 1 is a diagram of an exemplary communication system of the presentinvention;

FIG. 2 is a block diagram illustrating the basic subsystems of anexemplary communication system of the present invention; and

FIG. 3 is an exemplary diagram illustrating the relationship between thephysical and logical channels on the forward link;

FIG. 4 is an exemplary diagram illustrating the relationship between thephysical and logical channels on the reverse link;

FIGS. 5A and 5B are exemplary diagrams which illustrate of the use ofthe inter-cell □ power levels to control the forward supplementalchannel transmission, respectively;

FIG. 6 is an exemplary diagram of the spectrum of the receivedmulti-carrier signal;

FIG. 7A is a diagram of an exemplary reverse link pilot/control channelframe format;

FIG. 7B is an exemplary timing diagram illustrating the reverse linkhigh speed data transmission;

FIG. 7C is an exemplary timing diagram illustrating the use ofinter-cell □ power levels;

FIG. 7D is an exemplary timing diagram illustrating the use ofinter-carrier power levels;

FIG. 7E is an exemplary timing diagram illustrating the transmission ofthe EIB bits;

FIGS. 8A-8B are exemplary timing diagram showing the transitions to thesuspended and dormant modes and exemplary state diagram showing thetransitions between the various operating modes, respectively;

FIG. 8C is an exemplary diagram showing a scenario wherein a remotestation operating in the suspended mode sends a location update messageupon detecting a new pilot;

FIGS. 9A-9B are exemplary diagrams illustrating the protocol for a basestation initiated transitions from the suspended and dormant modes tothe traffic channel mode, respectively; and

FIGS. 9C-9D are exemplary diagrams illustrating the protocol for aremote station initiated transitions from the suspended and dormantmodes to the traffic channel mode, respectively; and

FIG. 10 is a flow diagram of a method for constructing and transmittinga message indicative of a rate of data and a time interval to transmit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS I. System Description

Referring to the figures, FIG. 1 represents an exemplary communicationsystem. One such system is the CDMA communication system which conformsto the IS-95 standard. Another such system is described in theaforementioned U.S. patent application Ser. No. 08/654,443. Thecommunication system comprises multiple cells 2 a-2 g. Each cell 2 isserviced by a corresponding base station 4. Various remote stations 6are dispersed throughout the communication system. In the exemplaryembodiment, each of remote stations 6 communicates with zero or morebase station 4 on the forward link at each traffic channel frame orframe. For example, base station 4 a transmits to remote stations 6 aand 6 j, base station 4 b transmits to remote stations 6 b and 6 j, andbase station 4 c transmits to remote stations 6 c and 6 h on the forwardlink at frame i. As shown by FIG. 1, each base station 4 transmits datato zero or more remote stations 6 at any given moment. In addition, thedata rate can be variable and can be dependent on thecarrier-to-interference ratio (C/I) as measured by the receiving remotestation 6 and the required energy-per-bit-to-noise ratio (E_(b)/N₀). Thereverse link transmissions from remote stations 6 to base stations 4 arenot shown in FIG. 1 for simplicity.

A block diagram illustrating the basic subsystems of an exemplarycommunication system is shown in FIG. 2. Base station controller 10interfaces with packet network interface 24, PSTN 30, and all basestations 4 in the communication system (only one base station 4 is shownin FIG. 2 for simplicity). Base station controller 10 coordinates thecommunication between remote stations 6 in the communication system andother users connected to packet network interface 24 and PSTN 30. PSTN30 interfaces with users through the standard telephone network (notshown in FIG. 2).

Base station controller 10 contains many selector elements 14, althoughonly one is shown in FIG. 2 for simplicity. One selector element 14 isassigned to control the communication between one or more base stations4 and one remote station 6. If selector element 14 has not been assignedto remote station 6, call control processor 16 is informed of the needto page remote station 6. Call control processor 16 then directs basestation 4 to page remote station 6.

Data source 20 contains the data which is to be transmitted to remotestation 6. Data source 20 provides the data to packet network interface24. Packet network interface 24 receives the data and routes the data toselector element 14. Selector element 14 sends the data to each basestation 4 in communication with remote station 6. In the exemplaryembodiment, each base station 4 maintains data queue 40 which containsthe data to be transmitted to remote station 6.

The data is sent, in data packets, from data queue 40 to channel element42. In the exemplary embodiment, on the forward link, a data packetrefers to a fixed amount of data to be transmitted to the destinationremote station 6 within one frame. For each data packet, channel element42 inserts the necessary control fields. In the exemplary embodiment,channel element 42 CRC encodes the data packet and control fields andinserts a set of code tail bits. The data packet, control fields, CRCparity bits, and code tail bits comprise a formatted packet. In theexemplary embodiment, channel element 42 encodes the formatted packetand interleaves (or reorders) the symbols within the encoded packet. Inthe exemplary embodiment, the interleaved packet is scrambled with along PN code, covered with a Walsh cover, and spread with the shortPN_(I) and PN_(Q) codes. The spread data is provided to RF unit 44 whichquadrature modulates, filters, and amplifies the signal. The forwardlink signal is transmitted over the air through antenna 46 on forwardlink 50.

At remote station 6, the forward link signal is received by antenna 60and routed to a receiver within front end 62. The receiver filters,amplifies, quadrature demodulates, and quantizes the signal. Thedigitized signal is provided to demodulator (DEMOD) 64 where it isdespread with the short PN_(I) and PN_(Q) codes, decovered with theWalsh cover, and descrambled with the long PN code. The demodulated datais provided to decoder 66 which performs the inverse of the signalprocessing functions done at base station 4, specifically thede-interleaving, decoding, and CRC check functions. The decoded data isprovided to data sink 68.

The communication system supports data and message transmissions on thereverse link. Within remote station 6, controller 76 processes the dataor message transmission by routing the data or message to encoder 72. Inthe exemplary embodiment, encoder 72 formats the message consistent withthe blank-and-burst signaling data format described in theaforementioned U.S. Pat. No. 5,504,773. Encoder 72 then generates andappends a set of CRC bits, appends a set of code tail bits, encodes thedata and appended bits, and reorders the symbols within the encodeddata. The interleaved data is provided to modulator (MOD) 74.

Modulator 74 can be implemented in many embodiments. In the firstembodiment, the interleaved data is covered with a Walsh code whichidentifies the data channel assigned to remote station 6, spread with along PN code, and further spread with the short PN codes. The spreaddata is provided to a transmitter within front end 62. The transmittermodulates, filters, amplifies, and transmits the reverse link signalover the air, through antenna 60, on reverse link 52.

In the second embodiment, modulator 74 functions in the same manner asthe modulator of an exemplary CDMA system which conforms to the IS-95standard. In this embodiment, modulator 74 maps the interleaved bitsinto another signal space using Walsh code mapping. Specifically, theinterleaved data is grouped into groups of six bits. The six bits aremapped to a corresponding 64-bits Walsh sequence. Modulator 74 thenspreads the Walsh sequence with a long PN code and the short PN codes.The spread data is provided to a transmitter within front end 62 whichfunctions in the manner described above.

For both embodiments, at base station 4, the reverse link signal isreceived by antenna 46 and provided to RF unit 44. RF unit 44 filters,amplifies, demodulates, and quantizes the signal and provides thedigitized signal to channel element 42. Channel element 42 despreads thedigitized signal with the short PN codes and the long PN code. Channelelement 42 also performs the Walsh code mapping or decovering, dependingon the signal processing performed at remote station 6. Channel element42 then reorders the demodulated data, decodes the de-interleaved data,and performs the CRC check function. The decoded data, e.g. the data ormessage, is provided to selector element 14. Selector element 14 routesthe data and message to the appropriate destination (e.g., data sink22).

The hardware, as described above, supports transmissions of data,messaging, voice, video, and other communications over the forward link.Other hardware architecture can be designed to support variable ratetransmissions and are within the scope of the present invention.

Scheduler 12 connects to all selector elements 14 within base stationcontroller 10. Scheduler 12 schedules high speed data transmissions onthe forward and reverse links. Scheduler 12 receives the queue size,which is indicative of the amount of data to be transmitted and otherpertinent information which is described below. Scheduler 12 schedulesdata transmissions to achieve the system goal of maximum data throughputwhile conforming to system constraints.

As shown in FIG. 1, remote stations 6 are dispersed throughout thecommunication system and can be in communication with zero or more basestations 4. In the exemplary embodiment, scheduler 12 coordinates theforward and reverse link high speed data transmissions over the entirecommunication system. A scheduling method and apparatus for high speeddata transmission are described in detail in U.S. patent applicationSer. No. 08/798,951, entitled “METHOD AND APPARATUS FOR FORWARD LINKRATE SCHEDULING”, filed Feb. 11, 1997, assigned to the assignee of thepresent invention and incorporated by reference herein.

II. Forward Link Channels

In the exemplary embodiment, the forward link comprises the followingphysical channels: pilot channel, sync channel, paging channel,fundamental channel, supplemental channel, and control channel. Theforward link physical channels facilitate transmissions of a variety oflogical channels. In the exemplary embodiment, the forward link logicalchannel comprises: the physical layer control, media access control(MAC), user traffic stream, and signaling. A diagram illustrating therelationship between the physical and logical channels on the forwardlink is shown in FIG. 3. The forward link logical channels are furtherdescribed below.

III. Forward Pilot Channel

In the exemplary embodiment, the forward pilot channel comprises anunmodulated signal which is used by remote stations 6 forsynchronization and demodulation. In the exemplary embodiment, the pilotchannel is transmitted at all times by base station 4.

IV. Forward Sync Channel

In the exemplary embodiment, the forward sync channel is used totransmit system timing information to remote stations 6 for initial timesynchronization. In the exemplary embodiment, the sync channel is alsoused to inform remote stations 6 of the data rate of the paging channel.In the exemplary embodiment, the structure of the sync channel can besimilar to that of the IS-95 system.

V. Forward Paging Channel

In the exemplary embodiment, the forward paging channel is used totransmit system overhead information and specific messages to remotestations 6. In the exemplary embodiment, the structure of the pagingchannel can be similar to that of the IS-95 system. In the exemplaryembodiment, the paging channel supports slotted mode paging andnon-slotted mode paging as defined by the IS-95 standard. Slotted andnon-slotted mode paging is described in detail in U.S. Pat. No.5,392,287, entitled “METHOD AND ΔPPARATUS FOR REDUCING POWER CONSUMPTIONIN A MOBILE COMMUNICATIONS RECEIVER”, issued Feb. 21, 1995, assigned tothe assignee of the present invention and incorporated by referenceherein.

VI. Forward Fundamental Channel

In the exemplary embodiment, forward traffic channels are used totransmit voice, data, and signaling messages from base stations 4 toremote stations 6 during a communication. In the exemplary embodiment,the forward traffic channels comprise fundamental channels andsupplemental channels. Fundamental channels can be used to transmitvoice traffic, data traffic, high speed data traffic, signaling traffic,physical layer control messages, and MAC information as shown in FIG. 3.In the exemplary embodiment, supplemental channels are only used totransmit high speed data.

In the exemplary embodiment, the fundamental channel is a variable ratechannel which can be used in one of two modes: the dedicated mode andthe shared mode. In the dedicated mode, the fundamental channel is usedto transmit voice traffic, IS-707 data traffic, high speed data traffic,and signaling traffic. In the exemplary embodiment, in the dedicatedmode, the signaling information is transmitted via dim-and-burst orblank-and-burst format as described in the aforementioned U.S. Pat. No.5,504,773.

Alternatively, if remote station 6 does not have an active circuitswitched service (e.g., voice or fax), the fundamental channel mayoperate in the shared mode. In the shared mode, the fundamental channelis shared among a group of remote stations 6 and the forward controlchannel is used to indicated to the remote station 6 when to demodulatethe assigned fundamental channel.

The shared mode increases the capacity of the forward link. When novoice or circuit-switched data service is active, using a dedicatedfundamental channel is inefficient because the fundamental channel isunder-utilized by intermittent packet data services and signalingtraffic. For example, the fundamental channel may be used to transmitthe TCP acknowledgments. In order to minimize the transmission delay inthe delivery of the signaling messages and data traffic, thetransmission rate of the fundamental channel is not reducedsignificantly. Several under-utilized fundamental channels can adverselyaffect the performance of the system (e.g., causing reduction in thedata rate of the high speed users).

In the exemplary embodiment, the use of the fundamental channel in theshared mode for a particular remote station 6 is indicated by anindicator bit sent on the forward control channel. This indicator bit isset for all remote stations 6 in the group when a broadcast message issent on the shared signaling channel. Otherwise, this indicator bit isset only for the particular remote station 6 for which a traffic channelframe is transmitted on the next frame.

VII. Forward Supplemental Channel

In the exemplary embodiment, the supplemental channel is used to supporthigh speed data services. In the exemplary embodiment, the supplementalchannel frame can be transmitted using one of a plurality of data ratesand the data rate used on the supplemental channel is transmitted to thereceiving remote station 6 by signaling (e.g., forward link schedule) onthe control channel. Thus, the data rate on the supplemental channeldoes not need to be dynamically determined by the receiving remotestation 6. In the exemplary embodiment, the Walsh codes used for thesupplemental channel are communicated to remote stations 6 via thelogical signaling channel which is transmitted on the forwardfundamental channel.

VIII. Forward Control Channel

In the exemplary embodiment, the control channel is a fixed rate channelassociated with each remote station 6. In the exemplary embodiment, thecontrol channel is used to transmit power control information and shortcontrol messages for the forward and reverse link schedule (see FIG. 3).The scheduling information comprises the data rate and the transmissionduration which have been allocated for the forward and reversesupplemental channels.

The usage of the fundamental channel can be regulated by signalingchannel frames which are transmitted on the control channel. In theexemplary embodiment, allocation of the logical signaling channel framesis performed by an indicator bit within the control channel frame. Theprocess fundamental indicator bit informs remote station 6 wheneverthere is information directed to remote station 6 on the fundamentalchannel in the next frame. FIG. 10 is a flow-chart of the operation.

The control channel is also used to transmit reverse power control bits.The reverse power control bits direct remote station 6 to increase ordecrease its transmission power such that the required level ofperformance (e.g., as measured by the frame error rate) is maintainedwhile minimizing interference to neighboring remote stations 6. Anexemplary method and apparatus for performing reverse link power controlis described in detail U.S. Pat. No. 5,056,109, entitled “METHOD ANDAPPARATUS FOR CONTROLLING TRANSMISSION POWER IN A CDMA CELLULAR MOBILETELEPHONE SYSTEM”, assigned to the assignee of the present invention andincorporated by reference herein. In the exemplary embodiment, thereverse power control bits are transmitted on the control channel every1.25 msec. To increase capacity and minimize interference, controlchannel frames are transmitted on the control channel only if there isscheduling or control information available for remote station 6.Otherwise, only power control bits are transmitted on the controlchannel.

In the exemplary embodiment, the control channel is supported by softhandoff to increase reliability in the reception of the control channel.In the exemplary embodiment, the control channel is placed in and out ofsoft handoff in the manner specified by the IS-95 standard. In theexemplary embodiment, to expedite the scheduling process for the forwardand reverse links, the control frames are each one quarter of thetraffic channel frame, or 5 msec for 20 msec traffic channel frames.

IX. Control Channel Frame Structure

The exemplary control channel frame formats for the forward and reverselink schedules are shown in Table 1 and Table 2, respectively. Twoseparate scheduling control channel frames, one for the forward link andanother for the reverse link, allow for independent forward and reverselink scheduling.

In the exemplary embodiment, as shown in Table 1, the control channelframe format for the forward link schedule comprises the frame type, theassigned forward link rate, and the duration of the forward link rateassignment. The frame type indicates whether the control channel frameis for the forward link schedule, the reverse link schedule, thesupplemental channel active set, or the erasure-indicator-bit (EIB) andfundamental frame indicator. Each of these control channel frame formatsis discussed below. The forward link rate indicates the assigned datarate for the upcoming data transmission and the duration field indicatesthe duration of the rate assignment. The exemplary number of bits foreach field is indicated in Table 1, although different number of bitscan be used and are within the scope of the present invention.

TABLE 1 Description # of Bits Frame Type 2 Forward Link Rate 4 Durationof Forward Link Rate Assignment 4 Total 10

In the exemplary embodiment, as shown in Table 2, the control channelframe format for the reverse link schedule comprises the frame type, thegranted reverse link rate, and the duration of the reverse link rateassignment. The reverse link rate indicates the data rate which has beengranted for the upcoming data transmission. The duration field indicatesthe duration of the rate assignment for each of the carriers.

TABLE 2 Description # of Bits Frame Type 2 Reverse Link Rate (Granted) 4Duration of Reverse Link Rate Assignment 12 (4 per carrier) Total 18

In the exemplary embodiment, base station 4 can receive reports fromremote station 6 indicating the identity of the strongest pilot withinthe active set of remote station 6 and all other pilots in the activeset which are received within a predetermined power level (P) of thestrongest pilot. This is discussed in detail below. In response to thispower measurement report, base station 4 can send a control channelframe on the control channel to identify a modified set of channels fromwhich remote station 6 is to receive supplemental channels. In theexemplary embodiment, the code channels corresponding to thesupplemental channels for all members of the active set are transmittedto remote station 6 via signaling messages.

The exemplary control channel frame format that is used by base station4 to identify the new set of base stations 4 from which supplementalchannel frames are transmitted is shown in Table 3. In the exemplaryembodiment, this control channel frame comprises the frame type and thesupplemental active set. In the exemplary embodiment, the supplementalactive set field is a bit-map field. In the exemplary embodiment, a onein position i of this field indicates that supplemental channel istransmitted from the i-th base station 4 in the active set.

TABLE 3 Description # of Bits Frame Type 2 Supplemental Active Set 6Total 8

The exemplary control channel frame format used to transmit the processfundamental channel indicator bit and the EIBs is shown in Table 4. Inthe exemplary embodiment, this control channel frame comprises the frametype, the fundamental and supplemental channel EIBs, and the processfundamental channel bit. The fundamental EIB indicates whether apreviously received reverse link fundamental channel frame was erased.Similarly, the supplemental EIB indicates whether a previously receivedreverse link supplemental channel frame was erased. The processfundamental channel bit (or the indicator bit) informs remote station 6to demodulate the fundamental channel for information.

TABLE 4 Description # of Bits Frame Type 2 EIB for Reverse FundamentalChannel 1 EIB for Reverse Supplemental Channel 1 Process FundamentalChannel 1 Total 5

X. Reverse Link Channels

In the exemplary embodiment, the reverse link comprises the followingphysical channels: access channel, pilot/control channel, fundamentalchannel, and supplemental channel. In the exemplary embodiment, thereverse link physical channels facilitate transmissions of a variety oflogical channels. The reverse link logical channels comprise: thephysical layer control, MAC, user traffic stream, and signaling. Adiagram illustrating the relationship between the physical and logicalchannels on the reverse link is shown in FIG. 4. The reverse linklogical channels are further described below.

XI. Reverse Access Channel

In the exemplary embodiment, the access channel is used by remotestations 6 to send origination message to base station 4 to request afundamental channel. The access channel is also used by remote station 6to respond to paging messages. In the exemplary embodiment, thestructure of the access channel can be similar to that of the IS-95system.

XII. Reverse Fundamental Channel

In the exemplary embodiment, reverse traffic channels are used totransmit voice, data, and signaling messages from remote stations 6 tobase stations 4 during a communication. In the exemplary embodiment, thereverse traffic channels comprise fundamental channels and supplementalchannels. Fundamental channels can be used to transmit voice traffic,IS-707 data traffic, and signaling traffic. In the exemplary embodiment,supplemental channels are only used to transmit high speed data.

In the exemplary embodiment, the frame structure of the reversefundamental channel is similar to that of the IS-95 system. Therefore,the data rate of the fundamental channel can vary dynamically and a ratedetermination mechanism is utilized to demodulate the received signal atbase station 4. An exemplary rate determination mechanism is disclosedin copending U.S. patent application Ser. No. 08/233,570, entitled“METHOD AND APPARATUS FOR DETERMINING DATA RATE OF TRANSMITTED VARIABLERATE DATA IN A COMMUNICATIONS RECEIVER,” filed Apr. 26, 1994, assignedto the assignee of the present invention and incorporated by referenceherein. Yet another rate determination mechanism is described in U.S.patent application Ser. No. 08/730,863, entitled “METHOD AND APPARATUSFOR DETERMINING THE RATE OF RECEIVED DATA IN A VARIABLE RATECOMMUNICATION SYSTEM”, filed Oct. 18, 1996, assigned to the assignee ofthe present invention and incorporated by reference herein. In theexemplary embodiment, signaling information is transmitted on thefundamental channel using dim-and-burst and blank-and-burst formats asdisclosed in the aforementioned U.S. Pat. No. 5,504,773.

XIII. Reverse Supplemental Channel

In the exemplary embodiment, the supplemental channel is used to supporthigh speed data services. In the exemplary embodiment, the supplementalchannel supports a plurality of data rates but the data rate does notchange dynamically during a transmission. In the exemplary embodiment,the data rate on the supplemental channel is requested by remote station6 and granted by base station 4.

XIV. Reverse Pilot/Control Channel

In the exemplary embodiment, the pilot and control information on thereverse link are time multiplexed on the pilot/control channel. In theexemplary embodiment, the control information comprises the physicallayer control and MAC. In the exemplary embodiment, the physical layercontrol comprises the erasure indicator bits (EIBs) for the forwardfundamental and supplemental channels, the forward power control bits,inter-cell Δ power levels, and inter-carrier power levels. In theexemplary embodiment, the MAC comprises the queue size which isindicative of the amount of information to be transmitted by remotestation 6 on the reverse link and the current power headroom of remotestation 6.

In the exemplary embodiment, two EIB bits are used to support theforward fundamental and supplemental channels. In the exemplaryembodiment, each EIB bit indicates an erased frame received two framesback of the respective forward traffic channel for which the EIB bit isassigned. The discussion on the implementation and use of EIBtransmission are disclosed in U.S. Pat. No. 5,568,483, entitled “METHODAND APPARATUS FOR THE FORMATTING OF DATA FOR TRANSMISSION”, assigned tothe assignee of the present invention and incorporated by referenceherein.

In the exemplary embodiment, the forward fundamental and/or supplementalchannel can be transmitted from the “best” set of base stations 4. Thistakes advantage of space diversity and can potentially result in lessrequired power for transmission on the forward traffic channels. Theinter-cell

A power levels is transmitted by remote station 6 on the pilot/controlchannel to indicate to base stations 4 the difference in the receivedpower levels from the base stations 4 that remote station 6 observes.Base stations 4 use this information to determine the “best” set of basestations 4 for the purpose of transmitting the forward fundamental andsupplemental channels.

In the exemplary embodiment, the inter-cell Δ power levels identify thepilot in the active set of remote station 6 with the highestenergy-per-chip-to-interference ratio (E_(c)/I₀) and all pilots in theactive set whose E_(c)/I₀ is within a predetermined power level (ΔP) ofthe pilot with the highest E_(c)/I₀. An exemplary method and apparatusfor measuring pilot power level is disclosed in U.S. patent applicationSer. No. 08/722,763, entitled “METHOD AND APPARATUS FOR MEASURING LINKQUALITY IN A SPREAD SPECTRUM COMMUNICATION SYSTEM”, filed Sep. 27, 1996,assigned to the assignee of the present invention and incorporated byreference herein. In the exemplary embodiment, three bits are used tospecify the index of the pilot (or the particular base station 4) withthe highest E_(c)/I₀ in the active set. In the exemplary embodiment, thenumber of pilots within the active set is limited to six. Thus, abit-map field of length five can be used to identify all pilots whoseE_(c)/I₀ is within ΔP of the strongest pilot. For example, a “one” canindicate that the pilot assigned to a particular bit position is withinΔP of the strongest pilot and a “zero” can indicate that the pilot isnot within ΔP of the strongest pilot. Therefore, a total of eight bitsare utilized for the inter-cell Δ power levels. This is indicated inTable 3.

TABLE 5 Description # of Bits Fundamental EIB 1 Supplemental EIB 1Inter-Cell Δ Power Levels 8 (3 + 5) Inter-Carrier Power Levels 12 (4bits/carrier) Queue Size 4 Power Headroom 4

An exemplary illustration of the use of the inter-cell Δ power levels tocontrol the forward supplemental channel transmission is shown in FIGS.5A and 5B. Initially, in FIG. 5A, base station A transmits thefundamental and supplemental channels, base station B transmits thefundamental channel, and base station C transmits the fundamentalchannel. Remote station 6 measures the forward link power and determinesthat the power level received from base station C is higher than thepower level received from base station A. Remote station 6 transmits theinter-cell Δ power levels to the base stations indicating thiscondition. The forward supplemental channel transmission is thenswitched from base station A to base station C in response thereto, asshown in FIG. 5B.

In the exemplary embodiment, the inter-carrier power levels is used toreport the received power on each of the carriers. In the multi-carrierenvironment, different carriers may fade independently and it ispossible that one or more of the carriers experience a deep fade whilethe remaining carriers are received significantly stronger. In theexemplary embodiment, remote station 6 can indicate the strength of thecarriers using the inter-carrier power levels.

An exemplary diagram of the spectrum of the received multi-carriersignal is shown in FIG. 6. It can be noted from FIG. 6 that carrier C isreceived weaker than carriers A an B. In the exemplary embodiment, thethree carriers are power controlled together by the forward powercontrol bits. Base stations 4 can use the inter-carrier power levels toassign different rates to each of the carriers. Alternatively, basestations 4 can use the inter-carrier power levels from remote station 6to increase the transmit gain for the weaker carrier such that allcarriers are received at the same energy-per-bit-to-interference ratio(E_(c)/I₀).

In the exemplary embodiment, a maximum of 16 rates for the reverse linkrequire scheduling. Thus, 16 levels of quantization is sufficient tospecify the power headroom of remote station 6. The maximum reverse linkrate can be expressed as:

$\begin{matrix}{{{{Max\_ Rate}{\_ Possible}} = {{{Current\_ Reverse}{\_ Rate}} + \left( \frac{Power\_ Headroom}{E_{b}{\_ Required}} \right)}},} & (1)\end{matrix}$where E_(b) _(—) Required is the energy-per-bit required for remotestation 6 to transmit on the reverse link. From equation (1) andassuming that 4 bits are used by base station 4 to indicate the grantedrate, a one-to-one relationship between the Max_Rate_Possible andPower_Headroom is possible if 4 bits are allocated to the power headroomparameter. In the exemplary embodiment, up to three carriers aresupported. Thus, the inter-carrier power levels comprise 12 bits toidentify the strength of each of the three carriers (4 bits percarrier).

Once base station 4 determines the granted rate, the duration of thereverse link rate assignment can be computed using the queue sizeinformation from remote station 6 through the following relationship:Queue_Size=Reverse_Rate·Assignment_Duration  (2)Therefore, the granularity of the queue size should be the same as thegranularity with which base station 4 uses to specify the duration ofthe rate assignment (e.g., 4 bits).

The above discussion assumes a maximum of 16 rates which requirescheduling and a maximum of three carriers. Different number of bits canbe used to support different number of carriers and rates and are withinthe scope of the present invention.

XV. Timing and Scheduling

As stated above, the control information is time-multiplexed with thepilot data. In the exemplary embodiment, the control information isspread within a frame such that continuous transmission occurs. In theexemplary embodiment, each frame is further divided into four equalcontrol frames. Thus, for a 20 msec frame, each control frame is 5 msecin duration. The partition of a forward channel frame into differentnumber of control frames can be contemplated and is within the scope ofthe present invention.

A diagram of an exemplary reverse link pilot/control channel frameformat is shown in FIG. 7A. In the exemplary embodiment, inter-cell Δpower levels 112 is transmitted in the first control frame of a frame,inter-carrier power levels 114 is transmitted in the second controlframe, EIB bits 116 are transmitted in the third control frame, andreverse link rate request (RL rate request) 118 is transmitted in thefourth control frame.

An exemplary timing diagram illustrating the reverse link high speeddata transmission is shown in FIG. 7B. Remote station 6 transmits the RLrate request in the fourth control frame of frame i to base station 4,at block 212. In the exemplary embodiment, the RL rate request comprisesthe 4-bit queue size and the 4-bit power headroom as described above.Channel element 42 receives the request and sends the request, alongwith the E_(b)/N₀ required by remote station 6, to scheduler 12 withinthe first control frame of frame i+1, at block 214. Scheduler 12receives the request in the third control frame of frame i+1, at block216, and schedules the request. Scheduler 12 then sends the schedule tochannel element 42 in the first control frame of frame i+2, at block218. Channel element 42 receives the schedule in the third control frameof frame i+2, at block 220. The forward link control frame containingthe reverse link schedule is transmitted to remote station 6 in thethird control frame of frame i+2, at block 222. Remote station 6receives the reverse link schedule within the fourth control frame offrame i+2, at block 224, and starts transmitting at the scheduled ratein frame i+3, at block 226.

Base station 4 uses the inter-cell Δ power levels, which is transmittedin the first control frame by remote station 6, to select the basestations 4 from which the supplemental channel is transmitted. Anexemplary timing diagram illustrating the use of inter-cell Δ powerlevels is shown in FIG. 7C. Remote station 6 transmits the inter-cell Δpower levels in the first control frame of frame i to base station 4 atblock 242. Channel element 42 receives the inter-cell Δ power levels andsends the information to base station controller (BSC) 10 in the secondcontrol frame of frame i, at block 244. Base station controller 10receives the information in the fourth control frame of frame i, atblock 246. Base station controller 10 then determines the new active setfor the supplemental channels in the first control frame of frame i+1,at block 248. Channel element 42 receives the forward link controlchannel frame containing the new supplemental active set and transmitsit on the forward link control channel at the third control frame offrame i+1, at block 250. Remote station 6 finishes decoding the forwardlink control channel frame within the fourth control frame of frame i+1,at block 252. Remote station 6 starts demodulating the new supplementalchannel at frame i+2, at block 254.

Base station 4 uses the inter-carrier power levels, which is transmittedin the second control frame by remote station 6, to assign rates to eachof the carriers to support remote station 6. An exemplary timing diagramillustrating the use of inter-carrier power levels is shown in FIG. 7D.Remote station 6 transmits the inter-carrier power levels in the secondcontrol frame of frame i to base station 4, at block 262. Channelelement 42 decodes the frame in the third control frame of frame i, atblock 264. Base station 4 receives the inter-carrier power levels andassigns rates to each of the carriers in the fourth control frame offrame i, at block 266. In the exemplary embodiment, the inter-carrierpower levels is not routed through the backhaul. Therefore, theappropriate action can take effect in the next frame after receiving theinter-carrier power levels. The forward link control channel framecontaining rates for each of the carriers is transmitted in the firstcontrol frame of frame i+1, at block 268. Remote station 6 finishesdecoding the forward link control channel frame in the second controlframe of frame i+1, at block 270. Remote station 6 starts demodulatingin accordance with the new rates for the carriers in frame i+2, at block272.

In the exemplary embodiment, the EIB bits are transmitted in the thirdcontrol frame on the pilot/control channel to indicate an erased framereceived on the fundamental and supplemental channels by remote station6. In the exemplary embodiment, the EIB bits can be used by high speeddata services as a layer-2 acknowledgment (ACK) or negativeacknowledgment (NACK) in place of the NACK radio link protocol (RLP)frames defined by the IS-707 standard entitled “TIA/EIA/IS-707 DATASERVICE OPTIONS FOR WIDEBAND SPREAD SPECTRUM SYSTEMS”. The EIB bits ofthe present invention are shorter and have less processing delays thanthe NACK RLP frames. An exemplary timing diagram illustrating thetransmission of the EIB bits is shown in FIG. 7E. Remote station 6receives data on the traffic channel on the forward link in frame i−2,at block 282. Remote station 6 finished decoding frame i−2 anddetermines whether the data frame is erased or not in the first controlframe of frame i, at block 284. The EIB bits indicative of the conditionof the data frames received in frame i−2 on the forward traffic channelare transmitted by remote station 6 in the third control frame of framei, at block 286.

The reverse link pilot/control channel frame format as described aboveis an exemplary format which minimizes the processing delays for theprocesses which utilize the information contained in the pilot/controlchannel frame. For some communication systems, some of the informationdescribed above are not applicable nor required. For example, acommunication system which operates with one carrier does not requirethe inter-carrier power levels. For other communication systems,additional information are utilized to implement various systemfunctions. Thus, pilot/control channel frame formats containingdifferent information and utilizing different ordering of theinformation can be contemplated and are within the scope of the presentinvention.

XVI. Remote Station Operating Modes

In the exemplary embodiment, to more fully utilize the available forwardand reverse link capacity, the traffic channels are released duringperiods of inactivity. In the exemplary embodiment, remote station 6operates in one of three modes: traffic channel mode, suspended mode,and dormant mode. The transition into and out of each mode is dependenton the length of the inactivity period.

An exemplary timing diagram showing the transitions to the suspended anddormant modes is shown in FIG. 8A and an exemplary state diagram showingthe transitions between the various operating modes is shown in FIG. 8B.The traffic (or activity) in the forward and/or reverse traffic channelsis represented by remote station 6 being in the traffic channel mode 312a, 312 b, and 312 c in FIG. 8A and traffic channel mode 312 in FIG. 8B.The period of inactivity, denoted as T_(idle), is the time durationsince the termination of the last data transmission. In the exemplaryembodiment, if the period of inactivity exceeds a first predeterminedidle period T_(s), remote station 6 is placed in suspended mode 314.Once in suspended mode 314, if the period of inactivity exceeds a secondpredetermined idle period T_(d), where T_(d)>T_(s), remote station 6 isplaced in dormant mode 316. In either suspended mode 314 or dormant mode316, if base station 4 or remote station 6 has data to communicate,remote station 6 can be assigned a traffic channel and brought back totraffic channel mode 312 (as shown in FIG. 8B). In the exemplaryembodiment, T_(s) is selected to be approximately one second and T_(d)is selected to be approximately 60 seconds, although other values forT_(s) and T_(d) can be selected and are within the scope of the presentinvention.

XVII. Remote Station Suspended Mode

Remote station 6 enters the suspended mode after the period ofinactivity exceeds a first predetermined idle period T_(s). In theexemplary embodiment, in the suspended mode, the traffic channel isreleased but the state information is retained by both remote station 6and base station 4 so that remote station 6 can be brought back to thetraffic channel mode in a short time period. In the exemplaryembodiment, the state information which is stored in the suspended modecomprises the RLP state, the traffic channel configuration, theencryption variables, and the authentication variables. These stateinformation are defined by the IS-95 and the IS-707 standards. Thetraffic channel configuration can comprise the service configuration,the connected service options and their characteristics, and powercontrol parameters. Since the state information are stored, remotestation 6 can be brought back to the traffic channel mode and assigned atraffic channel after reception of a channel assignment message.

In the exemplary embodiment, while in the suspended mode, remote station6 continuously monitor the paging channel in the non-slotted mode andprocesses the overhead messages which are broadcast to all remotestations 6 on the paging channel. Remote station 6 may send locationupdate messages to base station 4 in order to inform base stationcontroller 10 of its current location. An exemplary diagram showing ascenario wherein remote station 6 k, which operates in the suspendedmode, sends a location update message upon detecting a new pilot isshown in FIG. 8C. Remote station 6 k receives the pilots from basestations 4 i and 4 j and the new pilot from base station 4 k. Remotestation 6 k then transmits a location update message on the reverse linkwhich is received by base stations 4 i, 4 j, and 4 k. Remote station 6 kcan also send a suspended location update message if the pilot from oneof the base stations 4 drops below a predetermined threshold. In theexemplary embodiment, the suspended location update message istransmitted on the access channel.

In the exemplary embodiment, the location update messages are routed tobase station controllers 10 by base stations 4. Thus, base stationcontroller 10 is constantly aware of the location of remote station 6and can compose a channel assignment message and bring remote station 6to the traffic channel mode in the soft handoff mode.

XVIII. Remote Station Dormant Mode

In the exemplary embodiment, remote station 6 monitors the pagingchannel in slotted mode while in the dormant mode to conserve batterypower. In the exemplary embodiment, the dormant mode is similar to thatdefined by IS-707 standard.

In the exemplary embodiment, no call related state information isretained by base station 4 nor remote station 6 in the dormant mode andonly the state of the point-to-point protocol (PPP) is maintained byremote station 6 and base station 4. As a result, remote station 6 andbase station 4 traverse through the call setup process (which comprisesthe page, page response, and channel assignment) before remote station 6is assigned a traffic channel and brought back to the traffic channelmode.

XIX. Transition to Traffic Channel Mode

In the exemplary embodiment, the transitions of remote station 6 fromthe suspended or dormant mode to the traffic channel mode can beinitiated by either base station 4 or remote station 6. The exemplarydiagrams illustrating the protocol for a base station initiatedtransitions from the suspended and dormant modes to the traffic channelmode are shown in FIGS. 9A and 9B, respectively. Base station 4initiates the process if it has data to communication to remote station6. If remote station 6 is in suspended mode (see FIG. 9A), base station4 transmits a channel assignment message on the paging channel and datatransmission can occur shortly thereafter. If remote station 6 is in thedormant mode (see FIG. 9B), base station 4 first transmit a pagingmessage on the paging channel. Remote station 6 receives the pagingmessage and transmits a page response message in acknowledgment. Basestation 4 then transmits the channel assignment message. After a seriesof service negotiation messages, the call set up is completed and datatransmission can occur thereafter. As shown in FIGS. 9A and 9B, thetransition from the suspended mode to the traffic channel mode isquicker than the transition from the dormant mode to the traffic channelmode because the state of the call is maintained by both remote station6 and base station 4.

The exemplary diagram illustrating the protocol for the remote stationinitiated transitions from the suspended and dormant mode to the trafficchannel mode are shown in FIGS. 9C and 9D, respectively. Remote station6 initiates the process if it has data to communication to base station4. If remote station 6 is in the suspended mode (see FIG. 9C), remotestation 6 transmits a reconnect message to base station 4. Base station4 then transmits a channel assignment message and data transmission canoccur shortly thereafter. If remote station 6 is in the dormant mode(see FIG. 9D), remote station 6 first transmits an origination messageto base station 4. Base station 4 then transmits the channel assignmentmessage. After a series of service negotiation messages, the call set upis completed and data transmission can occur thereafter.

The present invention has been described by a number of physicalchannels which facilitate communication of the plurality of logicalchannels described above. Other physical channels can also be utilize toimplement additional functions which may be required for thecommunication system wherein the channels are used. Furthermore, thephysical channels described above can be multiplexed and/or combinedsuch that the required functions can be performed and these variouscombinations of the physical channels are within the scope of thepresent invention.

The previous description of the preferred embodiments is provided toenable any person skilled in the art to make or use the presentinvention. The various modifications to these embodiments will bereadily apparent to those skilled in the art, and the generic principlesdefined herein may be applied to other embodiments without the use ofthe inventive faculty. Thus, the present invention is not intended to belimited to the embodiments shown herein but is to be accorded the widestscope consistent with the principles and novel features disclosedherein.

1. A method for transmitting data comprising the steps of: transmitting,prior to and independent of said data transmission, a message indicativeof the rate of said data and a time interval over which said data willbe transmitted at said rate; and transmitting said data at said rateduring said time interval using a data transmission channel; whereinsaid message comprises: an indication of a frame type selected from aplurality of frame types including link schedule, channel active set,and erasure-indicator bit, wherein each of each of these frame types istransmitted at some time; an indication of said rate of said data; andan indication of said time interval; wherein said link scheduleindicates the duration of said data transmission; wherein said channelactive set indicates a set of base stations; and wherein saiderasure-indicator-bit indicates an erasure of previously receivedframes.
 2. The method of claim 1 wherein said link schedule is selectedfrom a group consisting of a forward link schedule and a reverse linkschedule.
 3. The method of claim 2 wherein said forward link schedule iscontained in a 10 bit forward link schedule message comprising: 2 bitsindicating that a frame is a forward link schedule message; 4 bitsindicating an assigned forward link rate of said data channel; and 4bits indicating the duration for which said data channel is assignedsaid forward link rate.
 4. The method of claim 2 wherein said reverselink schedule is contained in an 18 bit reverse link schedule messagecomprising: 2 bits indicating that a frame is a reverse link schedulemessage; 4 bits indicating a granted reverse link rate of said datachannel; and, 12 bits indicating the duration for which said datachannel is granted said reverse link rate, wherein each subset of 4 bitsrepresents a single carrier.
 5. The method of claim 1 wherein saidchannel active set is contained in an 8 bit channel active set messagecomprising: 2 bits indicating that a frame is a channel active setmessage; and, 6 bits indicating base stations in the active set, whereineach bit represents a base station.
 6. The method of claim 1 whereinsaid erasure-indicator-bit is contained in an 5 biterasure-indicator-bit message comprising: 2 bits indicating that a frameis an erasure-indicator-bit message; 1 bit indicating anerasure-indicator-bit for a fundamental data channel; 1 bit indicatingan erasure-indicator-bit for a supplemental data channel; and, 1 bitindicating demodulation of said fundamental channel.
 7. An apparatus fortransmitting comprising: a transmitter for transmitting, prior to andindependent of a data transmission, a message indicative of the rate ofsaid data and a time interval over which said data will be transmittedat said rate; a processor configured to form said message to include atleast an indication of a frame type selected from a plurality of frametypes including link schedule, channel active set, and erasure-indicatorbit, wherein the transmitter transmits each of these frame types istransmitted at some time, an indication of said rate of said data; andan indication of said time interval; wherein said link scheduleindicates the duration of said data transmission; wherein said channelactive set indicates a set of base stations; and, wherein saiderasure-indicator-bit indicates an erasure of previously receivedframes.
 8. The apparatus of claim 7 wherein said link schedule isselected from a group consisting of a forward link schedule and areverse link schedule.
 9. The apparatus of claim 8 wherein said forwardlink schedule is contained in a 10 bit forward link schedule messagecomprising: 2 bits indicating that a frame is a forward link schedulemessage; 4 bits indicating an assigned forward link rate of a datachannel; and 4 bits indicating the duration for which said data channelis assigned said forward link rate.
 10. The apparatus of claim 8 whereinsaid reverse link schedule is contained in an 18 bit reverse linkschedule message comprising: 2 bits indicating that a frame is a reverselink schedule message; 4 bits indicating a granted reverse link rate ofa data channel; and, 12 bits indicating the duration for which said datachannel is granted said reverse link rate, wherein each subset of 4 bitsrepresents a single carrier.
 11. The apparatus of claim 7 wherein saidchannel active set is contained in an 8 bit channel active set messagecomprising: 2 bits indicating that a frame is a channel active setmessage; and, 6 bits indicating base stations in the active set, whereineach bit represents a base station.
 12. The apparatus of claim 7 whereinsaid erasure-indicator-bit is contained in an 5 biterasure-indicator-bit message comprising: 2 bits indicating that a frameis an erasure-indicator-bit message; 1 bit indicating anerasure-indicator-bit for a fundamental data channel; 1 bit indicatingan erasure-indicator-bit for a supplemental data channel; and, 1 bitindicating the demodulation of said fundamental channel.
 13. Anapparatus for transmitting comprising: a transmitting means fortransmitting, prior to and independent of a data transmission, a messageindicative of the rate of said data and a time interval over which saiddata will be transmitted at said rate; a controller means configured toform said message to include at least an indication of a frame typeselected from a plurality of frame types including link schedule,channel active set, and erasure-indicator bit, wherein the transmittingmeans transmits each of these frame types at some time, an indication ofsaid rate of said data; and an indication of said time interval; whereinsaid link schedule indicates the duration of said data transmission;wherein said channel active set indicates a set of base stations; and,wherein said erasure-indicator-bit indicates an erasure of previouslyreceived frames.
 14. The apparatus of claim 13 wherein said linkschedule is selected from a group consisting of a forward link scheduleand a reverse link schedule.
 15. The apparatus of claim 14 wherein saidforward link schedule is contained in a 10 bit forward link schedulemessage comprising: 2 bits indicating that a frame is a forward linkschedule message; 4 bits indicating an assigned forward link rate of adata channel; and 4 bits indicating the duration for which said datachannel is assigned said forward link rate.
 16. The apparatus of claim14 wherein said reverse link schedule is contained in an 18 bit reverselink schedule message comprising: 2 bits indicating that a frame is areverse link schedule message; 4 bits indicating a granted reverse linkrate of a data channel; and, 12 bits indicating the duration for whichsaid data channel is granted said reverse link rate, wherein each subsetof 4 bits represents a single carrier.
 17. The apparatus of claim 13wherein said channel active set is contained in an 8 bit channel activeset message comprising: 2 bits indicating that a frame is a channelactive set message; and, 6 bits indicating base stations in the activeset, wherein each bit represents a base station.
 18. The apparatus ofclaim 13 wherein said erasure-indicator-bit is contained in an 5 biterasure-indicator-bit message comprising: 2 bits indicating that a frameis an erasure-indicator-bit message; 1 bit indicating anerasure-indicator-bit for a fundamental data channel; 1 bit indicatingan erasure-indicator-bit for a supplemental data channel; and, 1 bitindicating the demodulation of said fundamental channel.
 19. A methodfor transmitting data comprising the steps of: transmitting, prior toand independent of said data transmission, a message indicative of therate of said data and a time interval over which said data will betransmitted at said rate; transmitting said data at said rate duringsaid time interval using a data transmission channel; wherein saidmessage comprises: an indication of a frame type selected from aplurality of frame types including link schedule, channel active set,and erasure-indicator bit, wherein each of each of these frame types istransmitted at some time; an indication of said rate of said data; andan indication of said time interval; and, wherein said link schedule isa forward link scheduling information contained in a 10 bit forward linkschedule message comprising: 2 bits indicating that a frame is a forwardlink schedule message; 4 bits indicating an assigned forward link rateof said data channel; and 4 bits indicating the duration for which saiddata channel is assigned said forward link rate.
 20. A method fortransmitting data comprising the steps of: transmitting, prior to andindependent of said data transmission, a message indicative of the rateof said data and a time interval over which said data will betransmitted at said rate; transmitting said data at said rate duringsaid time interval using a data transmission channel; wherein saidmessage comprises: an indication of a frame type selected from aplurality of frame types including link schedule, channel active set,and erasure-indicator bit, wherein each of each of these frame types istransmitted at some time; an indication of said rate of said data; andan indication of said time interval; wherein said link schedule is areverse link scheduling information contained in an 18 bit reverse linkschedule message comprising: 2 bits indicating that a frame is a reverselink schedule message; 4 bits indicating a granted reverse link rate ofsaid data channel; and 12 bits indicating the duration for which saiddata channel is granted said reverse link rate, wherein each subset of 4bits represents a single carrier.
 21. A method for transmitting datacomprising the steps of: transmitting, prior to and independent of saiddata transmission, a message indicative of the rate of said data and atime interval over which said data will be transmitted at said rate;transmitting said data at said rate during said time interval using adata transmission channel; wherein said message comprises: an indicationof a frame type selected from a plurality of frame types including linkschedule, channel active set, and erasure-indicator bit, wherein each ofeach of these frame types is transmitted at some time; an indication ofsaid rate of said data; and an indication of said time interval; and,wherein said channel active set is contained in an 8 bit channel activeset message comprising: 2 bits indicating that a frame is a channelactive set message; 6 bits indicating base stations in the active set,wherein each bit represents a base station.
 22. A method fortransmitting data comprising the steps of: transmitting, prior to andindependent of said data transmission, a message indicative of the rateof said data and a time interval over which said data will betransmitted at said rate; transmitting said data at said rate duringsaid time interval using a data transmission channel; wherein saidmessage comprises: an indication of a frame type selected from aplurality of frame types including link schedule, channel active set,and erasure-indicator bit, wherein each of each of these frame types istransmitted at some time; an indication of said rate of said data; andan indication of said time interval; and, wherein saiderasure-indicator-bit is contained in an 5 bit erasure-indicator-bitmessage comprising: 2 bits indicating that a frame is anerasure-indicator-bit message; 1 bit indicating an erasure-indicator-bitfor a fundamental data channel; 1 bit indicating anerasure-indicator-bit for a supplemental data channel; and, 1 bitindicating demodulation of said fundamental channel.
 23. An apparatusfor transmitting comprising: a transmitter for transmitting, prior toand independent of a data transmission, a message indicative of the rateof said data and a time interval over which said data will betransmitted at said rate; a processor configured to form said message toinclude at least an indication of a frame type selected from a pluralityof frame types including link schedule, channel active set, anderasure-indicator bit, wherein the transmitter transmits each of theseframe types at some time, an indication of said rate of said data; andan indication of said time interval; and, wherein said link schedule isa forward link scheduling information contained in a 10 bit forward linkschedule message comprising: 2 bits indicating that a frame is a forwardlink schedule message; 4 bits indicating an assigned forward link rateof a data channel; and 4 bits indicating the duration for which saiddata channel is assigned said forward link rate.
 24. An apparatus fortransmitting comprising: a transmitter for transmitting, prior to andindependent of a data transmission, a message indicative of the rate ofsaid data and a time interval over which said data will be transmittedat said rate; a processor configured to form said message to include atleast an indication of a frame type selected from a plurality of frametypes including link schedule, channel active set, and erasure-indicatorbit, wherein the transmitter transmits each of these frame types at sometime, an indication of said rate of said data; and an indication of saidtime interval; and, wherein said link schedule is a reverse linkscheduling information contained in an 18 bit reverse link schedulemessage comprising: 2 bits indicating that a frame is a reverse linkschedule message; 4 bits indicating a granted reverse link rate of adata channel; and 12 bits indicating the duration for which said datachannel is granted said reverse link rate, wherein each subset of 4 bitsrepresents a single carrier.
 25. An apparatus for transmittingcomprising: a transmitter for transmitting, prior to and independent ofa data transmission, a message indicative of the rate of said data and atime interval over which said data will be transmitted at said rate; aprocessor configured to form said message to include at least anindication of a frame type selected from a plurality of frame typesincluding link schedule, channel active set, and erasure-indicator bit,wherein the transmitter transmits each of these frame types at sometime, an indication of said rate of said data; and an indication of saidtime interval; wherein said channel active set is contained in an 8 bitchannel active set message comprising: 2 bits indicating that a frame isa channel active set message; and, 6 bits indicating base stations inthe active set, wherein each bit represents a base station.
 26. Anapparatus for transmitting comprising: a transmitter for transmitting,prior to and independent of a data transmission, a message indicative ofthe rate of said data and a time interval over which said data will betransmitted at said rate; a processor configured to form said message toinclude at least an indication of a frame type selected from a pluralityof frame types including link schedule, channel active set, anderasure-indicator bit, wherein the transmitter transmits each of theseframe types at some time, an indication of said rate of said data; andan indication of said time interval; wherein said erasure-indicator-bitis contained in an 5 bit erasure-indicator-bit message comprising: 2bits indicating that a frame is an erasure-indicator-bit message; 1 bitindicating an erasure-indicator-bit for a fundamental data channel; 1bit indicating an erasure-indicator-bit for a supplemental data channel;and, 1 bit indicating demodulation of said fundamental channel.
 27. Anapparatus for transmitting comprising: a transmitting means fortransmitting, prior to and independent of a data transmission, a messageindicative of the rate of said data and a time interval over which saiddata will be transmitted at said rate; a processor configured to formsaid message to include at least an indication of a frame type selectedfrom a plurality of frame types including link schedule, channel activeset, and erasure-indicator bit, wherein the transmitter transmits eachof these frame types at some time, an indication of said rate of saiddata; and an indication of said time interval; and, wherein said linkschedule is a forward link scheduling information contained in a 10 bitforward link schedule message comprising: 2 bits indicating that a frameis a forward link schedule message; 4 bits indicating an assignedforward link rate of a data channel; and 4 bits indicating the durationfor which said data channel is assigned said forward link rate.
 28. Anapparatus for transmitting comprising: a transmitting means fortransmitting, prior to and independent of a data transmission, a messageindicative of the rate of said data and a time interval over which saiddata will be transmitted at said rate; a processor configured to formsaid message to include at least an indication of a frame type selectedfrom a plurality of frame types including link schedule, channel activeset, and erasure-indicator bit, wherein the transmitter transmits eachof these frame types at some time, an indication of said rate of saiddata; and an indication of said time interval; and, wherein said linkschedule is a reverse link scheduling information contained in an 18 bitreverse link schedule message comprising: 2 bits indicating that a frameis a reverse link schedule message; 4 bits indicating a granted reverselink rate of a data channel; and 12 bits indicating the duration forwhich said data channel is granted said reverse link rate, wherein eachsubset of 4 bits represents a single carrier.
 29. An apparatus fortransmitting comprising: a transmitting means for transmitting, prior toand independent of a data transmission, a message indicative of the rateof said data and a time interval over which said data will betransmitted at said rate; a processor configured to form said message toinclude at least an indication of a frame type selected from a pluralityof frame types including link schedule, channel active set, anderasure-indicator bit, wherein the transmitter transmits each of theseframe types at some time, an indication of said rate of said data; andan indication of said time interval; and, wherein said channel activeset is contained in an 8 bit channel active set message comprising: 2bits indicating that a frame is a channel active set message; and, 6bits indicating base stations in the active set, wherein each bitrepresents a base station.
 30. An apparatus for transmitting comprising:a transmitting means for transmitting, prior to and independent of adata transmission, a message indicative of the rate of said data and atime interval over which said data will be transmitted at said rate; aprocessor configured to form said message to include at least anindication of a frame type selected from a plurality of frame typesincluding link schedule, channel active set, and erasure-indicator bit,wherein the transmitter transmits each of these frame types at sometime, an indication of said rate of said data; and an indication of saidtime interval; and, wherein said erasure-indicator-bit is contained inan 5 bit erasure-indicator-bit message comprising: 2 bits indicatingthat a frame is an erasure-indicator-bit message; 1 bit indicating anerasure-indicator-bit for a fundamental data channel; 1 bit indicatingan erasure-indicator-bit for a supplemental data channel; and, 1 bitindicating demodulation of said fundamental channel.